HI guys. This is my goldfish Debbie. She lives in a 55 gallon tank with 3 other goldfish. The temp is usually between 73-75 degrees. I don’t know how old she is, I bought her about 3 months ago at the same size as she is now. Ever since I’ve gotten her, I haven’t seen her come up to the top of the tank. She stays at the bottom, and I have to throw food to the bottom, in order for her to eat. She also stays in one of the corners of the tank a lot. I just wanted to opinions on what this may be, lazy fish, swim bladder, or what? Thanks!